1. Field of the Invention
The present invention relates generally to ammunition and, more particularly, to tubular projectiles having both annular wings and interior canted vanes.
2. Description of Related Art
In the field of ammunition projectiles, there exists a continuing need to provide improved projectiles with longer range, better accuracy and reduced aerodynamic drag. Over the years, numerous projectile designs have been introduced that address one or more of these aspects.
A common approach to reducing drag is to provide a projectile that is hollow or tubular in shape. Recent United States patents including Flatau U.S. Pat. No. 4,301,736, Matthui U.S. Pat. No. 4,413,565, and Flatau U.S. Pat. No. 4,579,059, each describe tubular projectiles. The advantage provided by the tubular shape is less drag, longer range and increased impact force. Unfortunately, the tubular design is not aerodynamically stable, and despite the disclosures of Flatau U.S. Pat. No.4,579,059, tubular projectiles cannot carry as much explosive material as a solid projectile having the same diameter.
Other projectiles such as that disclosed in Romer, U.S. Pat. No. 4,153,223, provide solid high speed projectiles having wing-like air control passages which provide a stabilizing characteristic for the projectile. Unfortunately, these wings also impart a considerable degree of drag on the projectile thus limiting its range.
The concept of a rotating or spinning projectile is disclosed in Ballmann, U.S. Pat. No. 4,296,893 and Gobis, U.S. Pat. No. 4,627,357. Ballmann provides spin imparting passages in rings detachably connected to a projectile while it rests in the barrel of a gun or cannon, which rings fall away from the projectile after it leaves the barrel of the gun. The rings of Ballmann contain passageways which utilize the force of the propellant gas to impart a spin to the projectile as it leaves the barrel of the gun. Alternatively, Ballmann describes a central passageway within the projectile itself which channels the propellant gases up through the interior of the projectile in such a way as to impart spin as the projectile passes through the barrel of the gun.
It is advantageous to provide projectiles with spin so as to bring about stabilization of the projectile in flight. However, the spin imparted to the Ballmann projectile ceases once it leaves the barrel of the gun. Gobis, 4,627,357 addresses this problem by providing a helical fin and exterior fins to its tubular body to impart spin to the projectile during flight. However, the Gobis fins impart additional drag to the projectile in causing the spin, and therefore reduces its range. Furthermore, Gobis provides no convenient means for carrying an explosive charge.
The concept of an annular wing is well known in the art (e.g. Zborowski U.S. Pat. No. 2,918,006). An annular wing has been used in combination with canted vanes to provide a spinning annular wing for purposes of lift and stability, Herrmann U.S. Pat. Nos. 3,065,932 and 3,135,484. The spinning of an annular wing around a central axis stabilizes the air frame by the gyroscopic effect. However, the Zborowski design lacks any canted vanes, and the Herrmann design refers only to self propelled aircraft and not a projectiles at all. (Chiorky U.S. Pat. No. 2,691,495)